DynDNS et. al. are great for not having to put IP addresses in config files... I put the dyndns domain in the config and if I ever want to change the server location I just update it in one place, and the config stays the same. But what if I want to change the port number that's used? Is there an equivalent for ports - so that I can also get what port to connect to from some service just like I get the IP from DynDNS? Or what's another solution (besides not changing the ports)?
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What are you trying to accomplish by changing the ports? – Jeff Mar 15 '11 at 01:13
2 Answers
DynDNS and DNS in general has the main purpose of not having to remember a host by its IP address. The DynDNS part comes is mostly to solve the issue of people who don't have static IP addresses, and they occasionally get new IP addresses when their DHCP leases expire.
The original intention wasn't really meant to account for someone purposely changing their IP address or port numbers. Usually a service is on a well known port that doesn't change, such has 80 for http. Depending on the protocol, you could set up a well-known port, and then have it redirect to a different port. As an example, some websites will redirect port 80 to 8080, but this is protocol dependent. This also won't work for a lot of other protocols, and you're usually stuck with the port you choose.

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Using DynDNS I access three different machines behind the same router by simply adding a colon and the port number just as if I were adding it to a static IP address (ie myhome-computer.dyndns.biz:1234 ). Each port points to a different internal ip in the router. This works fine with my free host account. However, I am not aware of a port identifier that could report as the DynDNS host app does.

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